The use of breathing masks to secure a supply of oxygen is well known in connection with resuscitation, operations, and other medical and rescue procedures. These masks typically include soft parts often made from silicon, PVC or similar material, and which are therefore flexible enough to be adapted to a patient's anatomy in order to obtain a tight-fitting mask against the anatomy of the patient's face. The masks are usually retained in their proper position by straps that extend behind the head of the patient. These straps are either attached to the corners of the actual mask by means of suitable fixtures, or to a separate strap having a retaining ring arranged around the socket piece of the mask. Typically, the socket piece is a pipe stub adapted for connection to a breathing device protruding from the face of the mask. In designs where the mask has been entirely formed of soft materials, it has been found to be difficult to fasten the fixtures to the actual mask.